Subpartitioning a partitioned table

Question

Hi Experts,
I would like to sub-partition few of the hand picked partitions of a partitioned-table. Is it possible???
Below is my example partition table:
drop table part_tab purge;
create table part_tab (id number, name clob, dt date)
partition by range (dt) (
partition p1 values less than (to_date('01-2-2012', 'dd-mm-yyyy')),
partition p2 values less than (to_date('01-3-2012', 'dd-mm-yyyy')),
partition p3 values less than (to_date('01-4-2012', 'dd-mm-yyyy')),
partition p4 values less than (to_date('01-5-2012', 'dd-mm-yyyy')),
partition p5 values less than (to_date('01-6-2012', 'dd-mm-yyyy')),
partition p6 values less than (to_date('01-7-2012', 'dd-mm-yyyy')));
insert into part_tab select level, 'level-' || level, to_date( to_char(mod(level,25) + 1) || '-01-2012', 'dd-mm-yyyy') from dual connect by level < 100;
insert into part_tab select level, 'level-' || level, to_date( to_char(mod(level,25) + 1) || '-02-2012', 'dd-mm-yyyy') from dual connect by level < 100;
insert into part_tab select level, 'level-' || level, to_date( to_char(mod(level,25) + 1) || '-03-2012', 'dd-mm-yyyy') from dual connect by level < 100;
insert into part_tab select level, 'level-' || level, to_date( to_char(mod(level,25) + 1) || '-04-2012', 'dd-mm-yyyy') from dual connect by level < 100;
insert into part_tab select level, 'level-' || level, to_date( to_char(mod(level,25) + 1) || '-05-2012', 'dd-mm-yyyy') from dual connect by level < 100;
insert into part_tab select level, 'level-' || level, to_date( to_char(mod(level,25) + 1) || '-06-2012', 'dd-mm-yyyy') from dual connect by level < 100;
commit;
create index it_g_id on part_tab(id);
create index it_p_dt on part_tab(dt) local;
select index_name, status from user_indexes where table_name = 'PART_TAB';
select partition_name, status from user_ind_partitions where index_name in (select index_name from user_indexes where table_name = 'PART_TAB');Is it possible to sub-partition only partition p4 & p6?
Thanks for your time.
- P

Answer 1

>
I would like to sub-partition few of the hand picked partitions of a partitioned-table. Is it possible???
>
Yes and No - with a (possibly complex) explanation
No - it is not possible to create a subpartitioned table that does not have at least ONE subpartition for each partition. This wouldn't make sense anyway - if there is no subpartition for data to go to there is no point in having the partition at all so just don't create that partition.
Yes - it is possible to create custom sub-partitions for your hand-picked partitions. But the other partitions will still have at least one subpartition. If you don't create a subpartition template then Oracle will create a DEFAULT subpartition for them with a system generated name.
If you do create a subpartition template then it will be used for all partitions for which you do not specify custom subpartitioning.
Here is sample DDL based on yours
drop table part_tab1 cascade constraints
create table part_tab1 (id number, name clob, dt date)
partition by range (dt)
subpartition by list(id)
SUBPARTITION TEMPLATE(
  subpartition TEMP_2_AND_3 values (2, 3),
  subpartition TEMP_DEFAULT values (DEFAULT)
( partition p1 values less than (to_date('01-2-2012', 'dd-mm-yyyy')),
partition p2 values less than (to_date('01-3-2012', 'dd-mm-yyyy')),
partition p3 values less than (to_date('01-4-2012', 'dd-mm-yyyy')),
partition p4 values less than (to_date('01-5-2012', 'dd-mm-yyyy'))
  subpartition P4_1_2_3 values (1, 2, 3),
  subpartition P4_4_5_6 values (4, 5, 6),
  subpartition P4_DEFAULT values (DEFAULT)
partition p5 values less than (to_date('01-6-2012', 'dd-mm-yyyy')),
partition p6 values less than (to_date('01-7-2012', 'dd-mm-yyyy'))
  subpartition P6_7_8_9 values (7, 8, 9),
  subpartition P6_DEFAULT values (DEFAULT)
)Note that custom subpartitioning has been specified for partitions p4 and p6 the subpartitioning is different for those two partitions.
In this example I have also specified DEFAULT subpartitions for P4, P6 and the subpartition template so that all subpartition data has somewhere to go.
Any data that does not map to one of the partitions will raise an exception. For example
(INSERT into part_tab1 values (1, 'abc', to_date('07-7-2012', 'dd-mm-yyyy') - 1/24) 
ORA-14400: inserted partition key does not map to any partitionTo summarize
1. A subpartitioned table will ALWAYS have at least one subpartition for each partition
2. You can specify custom subpartitioning for any partition that is predefined (i.e. not for INTERVAL partitions).
3. The custom subpartitioning can be different for each partition
4. You can prevent inserting of data into the table by NOT providing a DEFAULT partition (as in your example). Attempts to insert such data will result in an ORA-14400 exception
5. You can also effectively prevent insertion into a partition by defining a subpartition (custom or DEFAULT) for a data value that will never exist in your data. No point in doing this since if no data can be inserted into the partition why have the partition to begin with?